A problem with minimally invasive, percutaneous procedures is the limited control the operator has over the penetrating instrument once the instrument in question has been introduced beneath the skin of a patient; that is, the operator has only direct control over the insertion depth.
To achieve a higher degree of control, steerable devices, like needles and stylets, have been suggested. The U.S. Patent Application No. 2004/0133168 discloses a needle guidance system comprising a stylet with a curved tip portion. The radius of curvature is, however, fixed, such that a specific curvature and a specific length of the curved portion have to be selected for the specific application at hand.
U.S. Pat. No. 6,652,491 is related to a stylet made from a shape-memory material. To introduce a curvature in the stylet, the stylet has to be heated.
A general object of the present invention is to provide an improved design for a steerable penetrating medical instrument, which enhances the manoeuvrability and thereby the control of the penetrating instrument.